(i) Technical Field
The present invention relates to an image data processing system.
(ii) Related Art
To increase the speed of print output, there is known a technique that performs parallel processing for print data by plural raster image processors (RIPs). A RIP is a device that develops data described in a page description language (hereinafter, referred to as PDL) such as the PostScript (registered trademark), into print image data, such as raster data or interval Data, that a print engine is able to handle. The processing for developing the PDL data into the print image data is occasionally called RIP processing.
Also, there is known an imposition function that arranges plural processing units (for example, pages) described in PDL data on one surface of a sheet side by side, or in a manner that the units are partially or completely superposed on each other. An example of the imposition function is n-up. Here, n is a natural number of two or larger. n-up is processing for printing n pages described in PDL data on one page of a sheet side by side. Also, another example of the imposition function is processing for completely superposing an image of a single logical page on an image of another logical page.
Hereinafter, a page defined with description in PDL data is called “logical page,” and a page of a sheet is called “physical page.” Hence, for example, 2-up represents printing two logical pages by arranging the two logical pages on a single physical page. In the case of a cut sheet, one of both surfaces of a cut sheet is typically a physical page. In the case of a rolled sheet, one of both surfaces a single sheet in the form of a final product after cutting (for example, a sheet of a book) is typically a single physical page.
The imposition processing arranges print image data of plural logical pages (or bands obtained by dividing the plural logical pages) subjected to the imposition, side by side or in a manner that the logical pages are partially or completely superposed, on a page buffer that holds print image data for a single physical page, or a band buffer that hold raster image data of bands obtained by dividing a single physical page into bands each having a predetermined number of pixel lines; and supplies the image data for the physical page formed on the buffer to a print engine in order of raster scanning.